1. Field of the Invention
The present invention relates to a camera having a finder optical system separate from a photographing optical system, and in particular relates to a zoom finder which is actuated in association with the zooming operation of the photographing optical system.
2. Description of the Related Art
In a camera having a view finder separate from a photographing optical system which is capable of zooming, it is preferable that the view finder be a zoom finder which is actuated in association with the zooming operation of the photographing optical system so as to visually confirm the angle of view which varies in accordance with the zooming operation. In such a zoom finder system, it is necessary to provide a mechanism which moves a variable power lens (or a plurality of power lenses) within the finder optical system along the optical axis. To this end, a support mechanism which supports the movable lens element(s) to move along the optical axis and a drive mechanism which moves the movable lens element are provided. The known support mechanism includes a guide shaft which extends in the optical axis direction of the photographing optical system and a lens frame which supports the movable lens element to move along the guide shaft. The known drive mechanism also includes a gear mechanism or a cam mechanism which moves the movable lens element in the optical axis direction, using the rotational force of a drive source such as a motor transmitted thereto.
In conventional zoom finders, the support mechanism and the drive mechanism are individually made of separate components. Consequently, the number of the components is increased and the components must be designed and arranged so as not to interfere with each other; consequently, neither miniaturization of the zoom finder nor reduction of the manufacturing cost thereof can be adequately achieved.
In particular, the guide shaft which movably supports the movable lens element and the rotational shaft which supports the gear mechanism or cam mechanism and which is independent from the guide shaft are spaced at a predetermined distance to extend in parallel within the finder so that no interference between the guide shaft and the rotational shaft occurs. This makes it difficult to miniaturize the finder. In recent trends, the photographing optical system or the finder optical system is assembled as a unit or a block, so that the elements thereof can be commonly used for different kinds of cameras. To this end, a miniaturization of the finder has become necessary.